Rice husk (RH) has now become a source for a number of silicon compounds, including silicon carbide, silica, silicon nitride, silicon tetrachloride, zeolite, and pure silicon. The applications of such materials derived from rice husks are very comprehensive. The methods of synthesizing these silicon-based materials from RHs and their applications are reviewed in this paper.

Silicon-Based Materials from Rice Husks and Their Applications

Porous silica and carbon derived materials from rice husk pyrolysis char

Boric oxide was used as a low melting additive to enhance the densification of forsterite. Results of liquid phase sintering have been compared with those of Al2O3 addition. Optimum density in case of pure Al2O3- and B2O3-added forsterite was found to be 2.06, 2.50 and 3.22 gm.cm−3 respectively under analogous thermal conditions. The maximum density was obtained at 3 wt% of B2O3 addition. Further addition of B2O3 reduced the density due to the development of excess vitreous phase.

Effect of B2O3 Addition on the Densification of Forsterite Prepared from Rice Husk Ash

Forsterite (2MgO.SiO2), a well-known non-feldspathic high frequency insulator (5 MHzs), was prepared by using magnesite/MgCO3and rice husk ash obtained after controlled burning as a source of MgO and SiO2 respectively and sintered at 1200°, 1250° and 1300°C for 1, 2, 3 and 4 hrs at each temperature. Effect of minor additive like A12O3 (added up to 5 wt %) on sintering was studied. Data were analysed using the empirical equation D = K log t + C and Arrhenius equation. Addition of 5 wt % Al2O3 has shown higher density (2.5 gm.cm−3) than that of pure forsterite (2.06 gm.cm−3) fired at 1300°C for 4 hours.

Studies on the Sinterability of Pure and Al2O3 Containing Forsterite Prepared from Rice Husk Ash

Partial and full stabilization of zirconia was attempted by using stabilizers like calcium chloride and bromide (10, 15 and 20 mol%). The green mixture was heated in powder form in the temperature range of 300° to 1300°C. The stabilization was studied through thermal analysis and powder X-ray diffraction techniques. The green mixture showed crystallinity only above 300°C. Crystal size increased with increase in calcination temperature. Calcined samples showed the presence of cubic/tetragonal phase along with a certain amount of monoclinic phase at room temperature. The intensity of the compound peak (30.2 2θ), where 10 mol% CaCl2 was used as stabilizer, increased rapidly with temperature up to 550°C, while in case of CaBr2 stabilizer it increased rapidly up to 750°C. Above these temperatures, marginal increase in intensity was observed in both the cases. A comparative study shows that below 800°C firing temperature, CaCl2 was more effective than CaBr2. However, above this temperature the reverse was obser...

B. Mondal

Papers

Studies on the Sinterability of Pure and Al2O3 Containing Forsterite Prepared from Rice Husk Ash

Partial and Full Stabilization of Zirconia by Calcium Chloride and Bromide Additives

Effect of B2O3 Addition on the Densification of Forsterite Prepared from Rice Husk Ash